The subtype specific roles of SK2 and SK3 channels in dopamine neurons of the substantia nigra

Dopamine neurons in the substantia nigra (SN) are strongly regulated by small-conductance calcium-activated potassium (SK) channels, previously attributed solely to SK3 expression. We demonstrate that SK2 is also present in SN dopamine neurons and is selectively localized to distal dendrites, unlike the uniform distribution of SK3. Pharmacological blockade of SK2 reduced the regularity of pacemaker activity without altering firing frequency. Unlike other cell types, dendritic SK2 in dopamine neurons did not influence fast glutamatergic synaptic transmission. These findings reveal a distinct role for SK2 in shaping dendritic excitability and pacemaking in SN dopamine neurons.